RESEARCH INTERESTS:Geochemistry and
Petrology of Subduction Zones, Modern and AncientGeochemical
Evolution of the Earth's MantlePetrogenesis of
Ultramafic Rocks Appalachian Geology
and Tectonics Meteoritic/Planetary
GeochemistryGeoscience Education

The science I do is very strongly instrument-based: I examine unusual and often difficult-to-measure elemental and isotopic tracers in rocks and waters as a means of gaining new insights into the origins and history of these materials, and to characterize and understand large-scale geochemical processes in the Earth. Toward these ends I manage the Geology department's rock analysis laboratories, which currently include a DC plasma emission spectrometer, our primary in-house tool for elemental analysis in rocks; and an X-ray powder diffractometer for the identification of minerals. We also prepare rock samples for trace metal analysis, particularly for Rare Earth Element (REE) studies, making use of ICP-MS facilities at the University of Boston, and other labs. My ongoing collaborations with researchers at the Department of Terrestrial Magnetism of the Carnegie Institution of Washington, and at the University of Maryland at College Park, provides us with access to these extensive analytical labs, including thermal ionization mass spectrometry facilities for traditional radiogenic isotopes, and their new doubly focusing, multicollector ICP-source MS instruments for B and Li isotopic analyses. A new addition to our in-house analytical capabilities (funded by NSF) is a regional electron microprobe/SEM facility. The instruments are housed at Florida International University, in the
Florida Center for Analytical Electron Microscopy , and we
have remote operation capabilities at USF via an Internet 2 operational
link, which means that we run the instrument in real time off of our
desktop computers in Tampa.

I currently maintain active research programs on modern subduction zones, and on the origins and metamorphic/tectonic evolution of igneous rock units in the southern Appalachians.

My subduction zone
studies follow two
separate, but related tracks:
1)
Elemental
fluxes
in subduction zones. Tracers such as Li, B, 11/10B and 10/9Be
indicate that materials and particularly fluids from the subducting
plate are involved in the generation of lavas at volcanic arcs. I
am examining a wide variety of volcanic and metamorphic materials to
constrain the physical processes behind fluid-mediated slab/mantle
chemical exchanges, and to quantify chemical fluxes between the Earth's
surface and its deep interior. My most recent efforts
have involved examining lithium isotope variations in suites of
arc lavas, volcanic rocks from several different "hotspot" settings,
and in arc mantle-derived ultramafic xenoliths with the goal of
characterizing both subduction-related fluxes of Li into the mantle,
and to try and identify subduction-generated Li reservoirs in the
mantle.

2) The
petrogenesis of igneous and metamorphic rocks at subduction zones. I am
studying the origins of igneous rocks from a variety of volcanic arcs
(the Woodlark Basin/New Georgia volcanic arc, the Mexican Volcanic
Belt, Kuril-Kamchatka arc, the Central American volcanic arc, and the
Aleutians, among others). I have also been examining the origins and
history of subduction-related metamorphic rocks, including samples from
the "subduction complex" association of the Catalina Schist (Calif.),
and in particular samples of diapiric serpentinites extruding as
seamounts in the forearc regions of the Marianas and Izu-Bonin arcs.

The mass transfer
pathways indicated by our forearc and cross-arc studies have led us to
examine the role that subduction plays in defining the chemical
signature of the deep mantle. A recently funded project examined the B
and Li isotopic systematics of lavas from Mt. Erebus, Antarctica, with
the intention of identifying subducted components in the deep mantle
sources of intraplate lavas. Newly funded research will use Li
isotope systematics along with B-Be-Li abundance systematics to assess
the development of mantle heterogeneities in subduction systems,
focusing on off-axis volcanism in Mexico and Guatemala; and to fully
characterize the OIB-source mantle reservoirs for Li isotopes.

My Appalachian research focuses primarily on unraveling the metamorphic evolution and igneous origins of
mafic/ultramafic rock associations in southwest North Carolina. These units are emplaced as part of late
Precambrian-age basement and lowermost cover sequence rocks, which represent forearc lithologies of an ancient
subduction system. In concert with Dr. Virginia Peterson of Grand Valley State University and Dr. Steve Yurkovich
at Western Carolina University, I pursue a combined field and laboratory-based research program oriented
toward undergraduates, which has focused on chemically characterizing the major rock units in the region, and on
detailed mapping and structural analysis efforts to infer the current orientation and deformational history of the
ultramafic units. Graduate student projects have focused on a careful documentation of the metamorphic histories of
these units, as a tool to use in the reconstruction of their tectonic histories. Our most recent efforts
(work-in-progress presented at the 2004 GSA SE-NE Sectional Meeting) have involved identifying occurrences of
Precambrian age mafic rocks within the Ashe Metamorphic Suite and associated units of the Eastern and Central Blue
Ridge, between Sylva and Burnsville, NC.

My work on Appalachian
mafic-ultramafic associations (thanks in large part to a highly
motivated graduate student!) has expanded to include the study of the
Balkan-Carpathian and Rhodopean ophiolites in the Balkans, which,
though substantially less metamorphosed than the complexes we examine
in the Blue Ridge, may be time correlative and thus may relate to the
same
global episode of extension. Aspects of our research on Appalachian
ultramafics and of subduction zone fluxes are currently trying to
dovetail, as we begin to pursue (from both perspectives) the
examination
of small, podiform ultramafic bodies in the Blue Ridge and Piedmont
belts of NC and VA, some of which preserve textures and mineralogies
remarkably similar to those of the Mariana forearc serpentinites.

A fledgling field of
inquiry in my lab, born of an undergraduate course ( GLY 4045: Moons, Planets, and Meteors: see below) and the excitment and energy of students
from that class, relates to meteor impacts, meteorite geochemistry and planetary sciences. I'm collaborating with
Harry McSween and coworkers at the University of Tennesee at Knoxville on examining B-Be-Li abundance variations in SNC
meteorites via ion microprobe and other means. I am also bringing this effort into the classroom in an Honors College
offering where Honor Natural Science course students learn the methods for, and participate in, the identificattion of
meteorites, and the exploration of new imagery coming back from active Mars orbiting probes.

Some of my most recent scholarly efforts relate to my interests (and recent experiences) in geoscience education.
I am involved in two active NSF Course, Curriclum and Laboratory Improvement Program projects: the first examines
the use of remote instrumentation in the classroom, making use of the FCAEM SEM and microprobe; and the second focuses
on the development and testinng of multidisciplinary geoscience educational materials ("MARGINS Mini-Lessons")
based on the data and discoveries supported by the NSF-MARGINS Program. I am also engaged in an effort to define
"characteristic suites" of igneous and metamorphic rocks for classroom use - this project is running as a
series of graduate and undergraduate field and seminar courses, focusing on the geology of the Grayson Highlands region
of SW Virginia, with the objective of establishing reference suites of samples from the volcanogenic Mount Rogers
Formation, and overlying sedimentary units of the Konnarock Formation and Chilhowee Group.

I am working with my USF colleague Dr. Len Vacher to develop a geoscience education graduate degree track at USF, to try and meet the needs of a growing number of students who want to pursue graduate training in Geology toward teaching in secondary education community colleges and small four-year institutions, where the need for such an instructional skillset is critical.
Please contact me if you are interested in pursuing an MS or Ph.D. degree in Geology with an educational focus!